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Liver Function Tests
This lecture by Dr. Bruce Clayton occurred on Thursday September 2nd and Tuesday September 7th. Back to RX 413 - Therapeutics Study Materials Required reading: *Lecture handout, *Helms, RA and Quan, DJ, eds. Textbook of Therapeutics, Drug and Disease Management, 8th ed., Lippincott, Williams and Wilkins, Philadelphia, 2006: 98-101 Handouts *Tests to Evaluate and Monitor Liver Function PPT *Liver Function Tests Handout Panopto *Thursday September 2nd *Tuesday September 7th Objectives Edited by Coastermonger 15:49, September 23, 2010 (UTC) Describe the gross anatomy of the liver with respect to size, consistency and anatomic location. The liver is a reddish brown organ with four lobes of unequal size and shape. A human liver normally weighs between 1.4–1.6 kg (3.1–3.5 lb), and is a soft, pinkish-brown, triangular organ. It is both the largest internal organ (the skin being the largest organ overall) and the largest gland in the human body. It is located in the right upper quadrant of the abdominal cavity, resting just below the diaphragm. The liver lies to the right of the stomach and overlies the gallbladder. It is connected to two large blood vessels, one called the hepatic artery and one called the portal vein. The hepatic artery carries blood from the aorta whereas the portal vein carries blood containing digested nutrients from the small intestine and the descending colon. These blood vessels subdivide into capillaries which then lead to a lobule. Each lobule is made up of millions of hepatic cells which are the basic metabolic cells. Describe the anatomy of the liver with respect to the following: lobule, portal vein, hepatic artery, central vein, intrahepatic sinusoids & Kupffer cells, biliary canaliculi, common bile duct, cystic duct, ampulla/papilla of Vater. Distinguish between vessels that flow into vs out of the liver, including in your discussion, the “portal triad”. Vessels that flow into the liver and mix in the Sinusoids include: *The hepatic Artery - containing oxygen rich, nutrient poor blood fresh from the heart following the aorta and celiac trunk *The portal vein system - containing nutrient rich, oxygen poor blood fresh from the GI tract. Vessels that flow out of the liver *The central vein, which leads to the Hepatic vein that empties into the inferior vena cava (IVC) The "Portal Triad" is a collection of 3 vessels that can be found clustered together in 3's around the central vein of a liver lobule. It consists of: *The portal vein *The hepatic artery *The intrahepatic biliary duct List functions that the liver performs under each of the following categories: excretory, synthetic, metabolic and storage. Excretory *The liver conjugates bilirubin, makes and excretes bile and bile salts into the duodenum for the purpose of emulsifying fats Synthetic *The liver synthesizes all major plasma proteins, including albumin & the coagulation proteins. *It also synthesizes transport proteins essential for the transport of hormones, vitamins, cholesterol (lipoproteins), and other substrates *it does NOT synthesize the immunoglobins. Describe the production and conjugation of bilirubin, including the important clinical significance of unconjugated (indirect), conjugated (direct) bilirubin, and total bilirubin. Describe how to classify hyperbilirubinemia as pre-hepatic, intrahepatic, or post-hepatic and list potential causes associated with each. Describe the expected color of the stools, color of urine, and predominant type of bilirubinemia for pre-hepatic vs post-hepatic causes of jaundice. List which liver function tests are included in the term “transaminases”. Define the following acronyms, list the primary sources and clinical significance of each of the following liver enzymes: AST, ALT, GGT, ALP, and LDH. Explain how elevations in liver enzyme tests can be roughly quantified as “mild,” “moderate,” or “pronounced”. List 5 classes of medicines that require periodic monitoring of liver function to help avert hepatotoxicity. Explain what serum albumin and the prothrombin time (PT) test reveal about liver function, and explain why the PT (INR) is an early indicator of decreased hepatic function. Explain why serum ammonia levels rise in the setting of liver failure, and its consequences. Explain what elevated urobilinogen levels reveal about liver function and why. Given a set of enzyme lab data, make a preliminary differentiation between liver disease, biliary disease, heart disease, and bone disease. Back to RX 413 - Therapeutics Category:RX 413 - Objectives